a(n) = 4*n^2 + 4*n - 1.

Terms

a(0) =7a(1) =23a(2) =47a(3) =79a(4) =119a(5) =167a(6) =223a(7) =287a(8) =359a(9) =439a(10) =527a(11) =623a(12) =727a(13) =839a(14) =959a(15) =1087a(16) =1223a(17) =1367a(18) =1519a(19) =1679a(20) =1847a(21) =2023a(22) =2207a(23) =2399a(24) =2599a(25) =2807a(26) =3023a(27) =3247a(28) =3479a(29) =3719